[R-390] GFCI issues

[Bill Hawkins]

Group,

A GFCI detects the differential current flow between hot and neutral
paths TO THE LOAD. A problem in the house wiring or distribution panel
can not trip a GFCI because it is on the wrong side of the detector.

Please read this Wikipedia link 
http://en.wikipedia.org/wiki/Residual-current_device

The article explains how a wire GFCI with no ground connection can
trip on a fault. When both the hot and the neutral pass through
the same toroid core in the same direction, no magnetic field
will be generated in the core if the currents are balanced, as
they must be if there is no fault. Faults before the core can not
be detected. The fault must be after the core.

Since the thing trips on about a 0.01 amp difference out of about
10 amps, it is pretty sensitive. Toroids are supposed to be self-
shielding, but a strong local field could be a problem.

For those who stubbornly insist that it is due to Chinese hackers
sending signals to your GFCI, I have a few rolls of audiophile-
quality tinfoil for shielding at $199 each.

Hope this helps,
Bill Hawkins